WordPress Error Warning Unable to modify header information / WordPress

Yesterday I helped a reader with his WordPress error, so I thought I might as well write an entry, in case we all run into this in the future. If you ever get this error (or warning) in your WordPress with the message:

Cảnh báo: Không thể sửa đổi thông tin tiêu đề - tiêu đề đã được gửi bởi (đầu ra bắt đầu tại //home/htdocs/wordpress/wp-config.php:1) trong /home/htdocs/wordpress/wp-login.php trên dòng 12

or something similar, you most likely messed up your wp-config.php leaving some unnecessary space inside.

Solution

1. Your download wp-config.php down via FTP (Direct edit if you have SSH access)
2. Open wp-config with your favorite editor and remove all spaces before “” and then “?>”

   

   

3. Upload and replace.

You should back up any files you’ve edited.